Cataracts, or a clouding of the lens of the eye, are a leading cause of visual loss among the elderly. Age-related cataracts affect more than half of all Americans over age 65.

Surgery to remove cataracts is the only effective treatment, and little is known about how to prevent them other than avoiding cigarette smoking and eating a diet rich in fruits and vegetables.

"Nutrition is suspected to be an important factor in cataract development," researcher William G. Christen, ScD, of Harvard Medical School, and colleagues write in the Archives of Ophthalmology.

"Because oxidative damage is a prominent feature of cataracts, one focus of nutrition research has been the link between dietary intake of nutrients with antioxidant potential, particularly vitamins E and C, and the risk of cataracts."

Previous observational studies have supported this notion, but researchers say there have been few controlled trials to properly evaluate the link between antioxidant vitamins and cataracts.

Antioxidant Supplements No Help Against Cataracts

In the study, researchers followed 11,545 healthy male doctors aged 50 and older. They were randomly assigned to receive either 500 IU of vitamin C or placebo daily or 400 IU of vitamin E or placebo every other day.

After eight years of follow-up, 593 cataracts were diagnosed in those who received vitamin C compared with 581 in those who got the vitamin C placebo. Results were similar in the vitamin E groups. There were 579 cataracts in the vitamin E group compared with 595 in the vitamin E placebo group. Researchers say these findings are in line with previous smaller studies on vitamin E supplementation and cataracts.

In both cases, researchers found no significant benefit of taking vitamin C or E supplements, either alone or in combination, in reducing the risk of cataracts among healthy, generally well-nourished middle-aged men.